1. Technical Field
The present invention relates to a door drive control apparatus and door drive control method for driving, for example, a train carriage door, at a predetermined speed, by means of a motor operated by a power converter.
2. Related Art
To date, when driving a door using a synchronous motor, a method has been known in which a position detector detects a polar position of the synchronous motor, calculates a speed from the detected polar position, and controls the speed of the synchronous motor. According to this method, where, for some reason, the actual polar position and the polar position information used for control are misaligned (referred to as a polar position misalignment), it can happen that abnormal situations occur, such as lack of thrust with respect to a door speed command value, stopping of the door, or overrun of the door in a direction opposite to the movement direction commanded by the speed command value (referred to as an inverse overrun). A known countermeasure to these kinds of abnormal situations is described in the door opening and closing apparatus of JP 2006-158009-A (paragraphs [0020] to [0025] and [0028] to [0033], FIGS. 1 to 4 etc.).
In the door opening and closing apparatus described in JP 2006-158009-A, inverse overrun is determined to be when a speed detection value of the synchronous motor exceeds a first setting value of a polarity opposite to that of the speed command value. A description is given of short circuiting an armature coil of the synchronous motor by means of a switch, and applying braking to the door, or short circuiting the motor armature coil by activating all switching elements of an upper arm or lower arm of a power converter, which drives the synchronous motor, making an output voltage zero (a zero voltage output), and applying braking to the door. A description is also given of carrying out a braking operation of the door until the speed of the door drops as far as or below a second setting value. By means of the heretofore described countermeasure, even in the event that the door falls into the inverse overrun condition due to polar position misalignment, this is detected immediately, and the door is safely stopped.
Normally, with a train carriage door drive control apparatus, in the event that a passenger or obstruction is caught in the door at the time of a closing operation, the door is caused to carry out a reopening and closing operation in order to free the object caught in the door. FIG. 9 shows a relationship between the speed command value and the speed detection value when the door is caused to carry out an opening operation again (the so-called reopening and closing operation), because an obstacle has come in contact with the door at the time of the door closing operation. In the reopening and closing operation, as the door is opened by switching the door speed command value from a closing direction to an opening direction, and subsequently, the door is closed by switching from the opening direction to the closing direction, the polarity of the speed command value changes, as shown in FIG. 9. At this time, as the door operates with a slight time lag with respect to the speed command value, a condition occurs in which the polarity of the speed command value and the polarity of the speed detection value become reversed, as shown at c in FIG. 9.
With the heretofore known technology of JP 2006-158009-A, when an overrun determination speed (the heretofore described first setting value) is set low for safety reasons, the condition in which the polarity of the speed command value and the polarity of the speed detection value become reversed at a time of the reopening and closing operation is misidentified as an inverse overrun condition. As a result thereof, it can happen that, even though it is a normal operation, the door is braked and stopped by carrying out the braking operation for an inverse overrun.
Further, when a passenger who runs onto the train lays a hand on a closing door, while the polarity of the speed command value is a polarity which closes the door, the polarity of the speed detection value is a polarity which opens the door. Consequently, in this case too, even though it is a normal operation, as the control apparatus misidentifies it as an inverse overrun, it applies braking and stops the door.
When, by so doing, the door stops and fails to close in this way, as the train starts moving after a member of staff has checked and locked the door, although there is no problem from a safety aspect, there has been a problem in that it interferes with the train's schedule.
Also, in the known technology of JP 2006-158009-A, as heretofore described, a technology is disclosed whereby, in the event of an actual inverse overrun of the door due to the polar position misalignment or the like, the door is braked by means of the zero voltage output. However, when the door overruns in the opening direction and, being unable to stop before a fully open position, bounces back from the fully open position, the speed detection value becomes zero at an instant in which the door bounces back from the fully open position. At this time, as the control apparatus stops the zero voltage output of the power converter, the power converter is gated off, and the motor falls into a free running condition. Consequently, a delay occurs in a braking of the motor, and there is a danger of the passenger being caught in the door and injured.
Furthermore, when an erroneous position detection value is input into the control apparatus due to a failure of a polar position detector, as a result of which the control apparatus misidentifies the inverse overrun condition, this causes the following kind of problem. That is, as this is not a case in which the door is actually overrunning, even though the power converter outputs the zero voltage, the control apparatus continues to misidentify an inverse overrun condition. As a result thereof, as the power converter will continue to output the zero voltage indefinitely, there has also been a problem in that a specific switching element becomes fixed in either an on condition or an off condition, causing an advancement in a depreciation of an instrument.